Zinc Oxide 99.9 +%, pure

Zinc oxide is an inorganic compound with the formula ZnO. ZnO is a white powder that is insoluble in water and it is often used as an additive in various materials and products, such as: rubber, plastic, ceramic, glass, cement, lubricants, paints, ointments, adhesives, sealants, pigments, food, batteries , ferrites, flame retardants and first aid tapes. Although it occurs naturally in the mineral zincite, most zinc oxide is produced synthetically

ZnO is a semiconductor of the II-VI semiconductor group. The addition of impurities to modulate their natural electrical properties (doping) of the semiconductor due to oxygen vacancies or zinc interstitials is type n.

This semiconductor has several favorable properties, including good transparency, high electron mobility, wide energy range where there are no electronic states (bandgap), and strong luminescence at room temperature. These properties are important for emerging applications: transparent electrodes in liquid crystal devices, power-saving or heat-shielding windows, and electronics such as thin-film transistors and light-emitting diodes.

Applications

The applications of zinc oxide powder are many, and the main ones are summarized below. Most applications take advantage of the oxide's reactivity as a precursor to other zinc compounds. For applications in materials science, zinc oxide has a high refractive index, high thermal conductivity, antibacterial properties and UV protection. Therefore, it is added to materials and products, including plastics, ceramics, crystals, cement, rubber, lubricants, paints, ointments, adhesives, sealants, concrete production, pigments, foods, batteries, ferrites, flame retardants. , etc.
Rubber manufacturing

Between 50% and 60% of ZnO is used in the rubber industry. Zinc oxide is used together with stearic acid in the vulcanization of rubber.18 50 51 The addition of ZnO also protects the mold rubber (see medical applications) and UV light.

-Ceramic industry

The ceramics industry consumes a significant amount of zinc oxide, especially ceramic glazes and fired compositions. The relatively high heat capacity, thermal conductivity and temperature stability of ZnO in combination with relatively low coefficients of expansion are desirable properties in ceramic production. ZnO affects the melting point and optical properties of varnishes, enamels and ceramic formulations. Low expansion zinc oxide, secondary flow improves the elasticity of varnishes by reducing the change in viscosity as a function of temperature and helps prevent cracking. By replacing BaO and PbO with ZnO, the heat capacity decreases and the thermal conductivity increases. Zinc in small amounts promotes the development of glossy and shiny surfaces. However, in moderate to large amounts it produces matte and crystalline surfaces. In terms of color, zinc has a complicated influence.

-Medicine

Zinc oxide as a mixture with about 0.5% Iron(III) oxide (Fe2O3) is called calamine and is used in calamine lotion. Two minerals, zincite and hemimorphite, are traditionally referred to as calamine. When mixed with eugenol, a ligand, zinc oxide eugenol is formed, which has applications as a regenerative and prosthetic treatment in dentistry.

Reflecting the basic properties of ZnO, fine oxide particles have deodorizing and antibacterial properties and are therefore added to materials such as cotton mill, rubber, oral care products, and food packaging. The improved antibacterial effect of fine particles compared to bulky material is not exclusive to ZnO and is also observed in other materials such as silver. This property is due to the larger surface area of the fine particles.

Zinc oxide is widely used to treat a variety of skin conditions, in products such as baby powder and rash creams, calamine cream, dandruff shampoos, and antiseptic ointments. It is also a component. on the tape (called "zinc oxide tape") used by athletes as a bandage to prevent soft tissue damage during their workout.

Zinc oxide can be used in ointments, creams and lotions to protect against sunburn and other skin damage caused by ultraviolet light. It has the broadest UVA and UVB reflectance spectrum approved for use in sunscreen in the United States by the Food and Drug Administration (FDA),  and is fully photostable. When used as an ingredient in a sunscreen, zinc oxide blocks both UVA (320-400 nm) and UVB (280-320 nm) from ultraviolet light. Zinc oxide and the other more common sunscreen, titanium dioxide, are considered non-irritating, non-allergenic, and non-comedogenic. However, the zinc of zinc oxide is easily absorbed by the skin.

Many sunscreens use zinc oxide nanoparticles (along with titanium dioxide particles) because these tiny particles do not scatter light and therefore do not appear white. There was concern that these could be absorbed through the skin. A study published in 2010 found that 0.23% to 1.31% (mean 0.42%) of blood zinc levels in venous blood samples. Trace amounts of zinc from ZnO nanoparticles applied to human skin for 5 days were also found in urine samples. found. In contrast, a comprehensive review of the medical literature in 2011 stated that no systemic absorption will be found in the literature

Zinc oxide nanoparticles may enhance the antibacterial activity of ciprofloxacin. ZnO nano with an average size of 20 nm and 45 nm has been shown to enhance the antibacterial activity of ciprofloxacin against Staphylococcus aureus and Escherichia coli in vitro. The potentiating effect on this nanomaterial is concentration dependent for all strains tested. This effect can be for two reasons. First, the zinc oxide nanoparticles can interfere with the NorA protein, which evolves to confer resistance on bacteria and has a pumping activity that mediates the outflow of hydrophilic fluoroquinolones from a cell. Second, the zinc oxide nanoparticles can interfere with the Omf protein, which is responsible for the penetration of quinolones into the cell.

-Cigar filters

Zinc oxide is a component of cigarette filters. A filter consisting of carbon impregnated with zinc oxide and iron oxide removes significant amounts of hydrogen cyanide (HCN) and hydrogen sulfide (H2S) from tobacco smoke without affecting the taste.

-Food additive

Zinc oxide is added to many food products, including breakfast cereals, as a source of zinc, a necessary nutrient (zinc sulfate is also used for the same purpose). Some prepackaged foods contain trace amounts of ZnO, even though it is not intended as a nutrient.

Zinc oxide was associated with dioxin contamination in pigs exported in 2008 during the Chilean pig crisis. Dioxin contamination was found to be due to zinc oxide used in pig feed.

-Pigment

Zinc white is used as a pigment in paints and is more opaque than lithopone, but less opaque than titanium dioxide. It is also used as a coating for paper. Chinese white is a special type of zinc white used in artists' pigments. The use of zinc white (zinc oxide) as a pigment in oil paint began in the mid-18th century. It has replaced white lead and was used by painters such as Böcklin, Van Gogh, Manet, Munch, among others. It is also a main ingredient in mineral composition (CI 77947)

-UV absorber

The micronization and nanoscale of zinc oxide and titanium dioxide provide strong protection against UV-UVA radiation and are used in tanning lotions,

as well as UV-blocking sunglasses for use in space and for protection while welding, according to research by scientists at the Jet Propulsion Laboratory (JPL).

-Coatings

Paints containing zinc oxide powder have been used as anticorrosive coatings for metals. They are especially effective in galvanizing iron. Iron is difficult to protect because its reactivity with organic coatings leads to brittleness and lack of adhesion. Zinc oxide paints retain their flexibility and adhesion to these surfaces for many years

ZnO strongly n-type doped with Al, Ga or In is transparent and conductive (~90% transparency, less resistivity ~10−4 Ω cm77). ZnO: Al coatings are used for windows that save energy or protect against heat. The cladding leaves the visible part of the spectrum, but reflects infrared (IR) radiation into the room (energy saving) or does not allow infrared radiation to enter the room (heat protection), depending on which side of the window the window is located on. liner.

Plastics, such as polyethylene naphthalate (PEN), can be protected by applying a zinc oxide coating. The coating reduces oxygen diffusion with PEN. Zinc oxide coatings can be used on polycarbonate (PC) in outdoor applications. The coating protects the PC from solar radiation and reduces the rate of oxidation and yellowing of the PC.

-Corrosion prevention in nuclear reactors

Zinc oxide reduced to 64Zn (the atomic mass isotope of zinc) is used in corrosion prevention in pressurized nuclear reactors. The reduction is necessary because the 64Zn is converted into radioactive 65Zn under irradiation from the neutrons of the reactor.

-Methane reforming

Zinc oxide (ZnO) is used as a pre-treatment step to remove hydrogen sulfide (H2S) from natural gas after hydrogenation of a compound with sulfur prior to methane reforming, which can poison the catalyst. At temperatures between 230, H2S turns into water by the following reaction:

H2S + ZnO → H2O + ZnS

Zinc sulfide (ZnS) is replaced with fresh zinc oxide when the zinc oxide is consumed.

Technical information

Empirical formula ZnO
Molar mass (M) 81,37 g/mol
Density (D) ca. 5,61
Melting point (mp)1975 °C
Solubility 0,0016 g/l (H₂O, 20 °C)
ADR 9 III • WGK 2
CAS No.[1314-13-2]
EG-Nr. 215-222-5 • UN-Nr. 3077

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